Depth sensing switch with tubular housing having a diaphragm encompassing a portion of said housing

ABSTRACT

A depth sensing device has an extensible resilient switch contact, contraposed behind a diaphragm, said contact having the form of a helical spring with both ends fixed and having its axis parallel to the surface of the diaphragm; said contact further flexes inwardly and establishes contact with a fixed contact when liquid pressure deflects the diaphragm. The diaphragm is formed by a flexible sheath that encompasses a portion of the tubular housing that houses the switch contacts, thereby sealing the contacts from the environment.

United States Patent Gamble 51 Dec. 19, 1972 [54] DEPTH. SENSING SWITCHWITH 2,750,480 6/1956 Freeman ..200/l68 G UB LAR HO ING HAVING A 1 AIPHRAGM EIECOMPASSING A FOREIGN PATENTS 0R APPLICATIONS PORTION OF SAIDHOUSING 1 323,532 $1923 great Britain V ,61 l 19 rance 83 N [721 InvenmRalph Gamble Chester 829,965 3/1960 Great Britain ..200/l66 BA 73 A sinee: Simmonds Precision Produ ts Inc. 1 s g Tatrytown c PrimaryExaminer-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye 1Filed; J 1971 Attorney-Edwin E. Greigg i 69 [21] APP! 153: [57] ABSTRACT1 i A depth sensing device has an extensible resilient "200/83 200/166 gswitch contact, contraposed behind a diaphragm, said 7 [58] F d 83 R 83B contact having the form of a helical spring with both C 0 re 2O0/83N 1BA ends fixed and having its axis parallel to the surface of thediaphragm; said contact further flexes inwardly and establishes contactwith a fixed contact when [56] References Cited liquid pressure deflectsthe diaphragm. The diaphragm UNITED STATES PATENTS is formed by aflexible sheath that encompasses a portion of the tubular housing thathouses the switch con- 3,453,962 7/1969 Strader ..200/83 N X tacts,thereby sealing the contacts from the environ- 2,l64,82l 7/1939 Katcherm 2,613,294 10/1952 McNea 2,902,668 9/1959 Savit ..200/83 W X 5 Claims,5 Drawing Figures PATENTED DEC 19 I972 FIG. I

5L F44 2 2 4 f0 INVENTOF RALPH S4 GAM LE ATTORNEYS DEPTH SENSING SWITCHWITH TUBULAR The presentinvention relates to depth sensing sensitiveswitches, and more particularly, tothose types of switches in whichadiaphragm is deflected inwardly causing a displacement which forces amovable contact into contact with astationary contact.

I-Ieretofore, pressure diaphragm switches responding to liquid or fluidpressure have been designed in such a manner that the diaphragm isdeflected in an axial direction'with the perimeter of said diaphragmbeing rigidly disposed in a plane normal to the axis of displacement. Inthis type of diaphragm switch, the diaphragm is usually of .thinflexible metal andmay be covered with a fluid-tight material such asrubber or a plastic. The diaphragm usually bears against a contact armdisposed behind the diaphragm, the arm being mounted resiliently so thatas the diaphragm deflects, it

to damage if it comes in contact with sharp or solid materials, andalso, it is susceptible to being stretched by pressures above that forwhich the switch may have been designed. Further, the switch diaphragmmust be subjected to substantially uniform, pressures or pres sures nearits center to cause actuation and toprevent localized stresses frombuckling or destroying the diaphragm as well as the contact arm beneaththe diaphragm. The switch, which is to be described later herein, is ofsuch a design that it may be used with fluids which include solidmaterials, without being susceptible to damage from such materials, andmay be actuated by localized pressures, as well as uniform pressures,which may occur with'the sensing of such materials.

In view of the foregoing, it is a principal object of this invention toprovide a pressure-sensitive switch for fluids which is insensitive tothe abusive effects of solids disposedwithin the fluids, and which isotherwise sturdy and strong.

It is a further object of this invention to provide a pressure-sensitiveswitch having a resilient movable contact which cannot be damaged bylateral forces and motions of the diaphragm, which are not along theaxis of the contact points.

It is still a further object of this invention to provide a pressureswitch which is inexpensive and easy to manufacture.

r 2 FIG. 3 shows another vertical cross-sectional view in which isincluded a support for the movable contact;

FIG. 4 shows another switch utilizing a round flexible diaphragm; and

' FIG. 5 is a fragmentary vertical cross-sectional view diameter ofthe'tube, and its length 13 being substantiallygreater than'its width.Mounted rigidly to the in-.

.ternal wall 14 of the plastic tube by screws 16 and 17 or other means,is an extensible, movable metal contact meanslS which may take the formof an extensible spring, its axis being longitudinai of the cylinderdescribed by the internal surface of the tube and midway between thelongitudinal edges of aperture 11, so

' that the contact is freely supported, adjacent to both ends of theaperture and located within and behind said aperture.

As best shown in FIG. 2, a curved stationary contact 18, supportedwithinthe plastic tube 10 by suitable means 19 and 20, is arranged toextend inwardly toward, but not to touch, the movable contact 15, e.g.,when in an inoperative condition as shown in the figure. The stationarycontact 18 has some degree of flexibility by virtue of its being a thinpiece of metal, but is essentially to be considered rigid.

Attached to the lowerend of plastic tube 10 is tube cap 21 which isaffixed by any suitable waterproof means such as cement; alternatively,the cap may be threadedly secured or clamped and provided with asuitable seal. The upper end of plastic tube 10 is covered by plasticpipe plug means 22, which has been bored to receive a plastic tube andis affixed thereto in any waterproof manner, such as described relativeto tube cap 21. The plastic pipe plug means 22 is further provided witha bore to allow conductor wires 23 and 24 to pass therethrough with theconductor being suitably sealed by a seal means indicated at 25.

The conductor wire 23 is attached at point 16 while conductor wire 24 isaffixed at point l9,the upper ends of each wire arranged to be suitablyconnected to the power supply means and indicating means, neither of Itis yet another object of this invention to provide an additional supportsurface for the movable contact.

The invention will be better understood and further objects andadvantages will become more apparent from a reading of the followingspecification, taken in conjunction with the drawing in which:

which is shown. v

The flexible boot means 26 is stretched over the plastic tube 10 in sucha manner that it circumferentially encompasses the tube in the area ofthe longitudinal aperture 11 and thereby effectively seals the entirearea, by surface contact around the aperture, to prevent fluids fromgaining access to the contacts when the switch is immersed in a liquid.It is evident that the switch is designed to be placed into the top of afluid tank with plastic tube 10 extending downwardly to any desiredlength, such as indicated at 27, to the level at which fluid pressure isto be sensed. When said fluid pressure is of sufficient force to urgethe flexible boot 26 into aperture 11 into contact with movable contact15, said contact will touch stationary contact 18, and a signal will betransmitted through wires 23 and 24 to an indicator (not shown).

FIG. 3 illustrates an additional embodimentof this invention, showingsupport surface 28 added to the construction of FIG. 2. Plastic rod 29is closely fitted to the inner diameter of plastic tube 10, suitablyslotted to receive stationary contact 18, and oppositely dished to theapproximate shape that boot 26'will assume when subjected to fluidpressure. The rod 29 is suitably slotted to receive the ends of movablecontact 15, and

stationary contact 18, which is affixed to rod 29 instead of plastictube in this embodiment.

1 Rod 29 is'assembled with stationary contact 18 held by screws 19 and20 to rod 29, screw 19 also being arranged to hold the lug end of wire24 in electrical contact with contact 18, and movable contact isassembledf in its proper position and affixed to rod 29 by screws 16 and17 which extend through plastic tube 10 holding the assembly in place,including the electrical connection of the lug end of wire 23 to contact15 by screw 16. The flexible boot 26 and the end caps and seals areassembled as hereinbefore described in connection with FIG. 1.

It will be now clear to those skilled in the art that sur- 2 face 28hasbeen added to give support to the flexible diaphragm after contactbetween movable contact 15 and stationary contact 18 has been made. Oncethe contacts are closed, there is no requirement for the "diaphragm todeflect and farther; however, with a further increase in fluid pressureand no support, the flexible boot 26 will be forced farther into theaperture I ll inplastictube 10 causing stretching and high localizedstresses to develop in the boot 26 at the edges of i said aperture. Bythe addition of the suitably shaped support surface 28, the flexible,boot will deflect only until-it is held inintimate contact with thissupport surface; at that time fluid pressure will be supported both bythe support surface and by the compressive strength of the bootmaterial, which is considerably greater than its strength as a membrane,allowing the switch to be used at great pressures without thedamagewhich could otherwise be sustained.

,.screws 36 and 37. The coiled movable contact means 15 is afiixed byboth ends to case 30 by means of screws 38 and 39 which enter suitablethreaded recesses which have been provided into the edge of case 30 indiametrically opposed positions. Diaphragm 40 is made of flexiblenon-metallic material and is held in place over v the edge of case 30 byclamping ring 41, which is suitably screw-threaded and attached to case30. In this switch the diaphragm also acts as a seal between the case 30and the clamping ring 41 A wire which enters perforation 43 in the case30 is secured as at 36 and the wire 44, which also extends through theperforation, is. attached at 38. The point of entry of the wires 42 and44, into the casing is later suitably sealed in any convenient manner.

. The switch means and its case 30 are supported'by' means 45 which canbe madeof any lengthto support the switch means at any required depthposition within abodyoffluid.

A still further embodiment of this invention is shown in FIG. 5, whereinthe carrier means forithe switch is not provided with the aperture inthe sidewall as previously explained, but instead has a smoothuninterrupted exterior as shown and the'c'ontacts are suitablypositioned in the end wall, as shown. In this concept the plastic pipeis formed with an annular'recess into which is frictionally and tightlyreceived theinsulation member 51, the latter forming a support for anadjustable contact member 52 that is threadedly secured therein, as wellas serving as a support for a flexible contact 53 which is securedthereto by means 54 The perimeter of the wall is provided with aleak-proof cement or other adhesive and thereafter the flexiblecupshaped diaphragm 56 is secured thereto completely encompassing theoperative elements; It will be apparent that the cup-shaped diaphragmcan be retained to the tubular body also by a clamping ring member.

It will-be evident to those skilled in the art that any number ofswitches may be supported within a body of fluid to sense pressures atvarious points within the body of fluid. Also, it is'to be understoodthat the actuation pressure is a function vof the tension in the movablecoiled contact, spacing between the contacts, and. the boot thicknesswhich can be adjusted during design or at assembly or, by addingsuitable known means, may be made adjustable after assembly.

It will be also recognized that the embodiments shown encompass only afew of those which can be devised using the basic principles taught inthis disclosure and that other physical changes .may be made thereinwhich do notdepart-from the spirit of this invention.

What is claimed is: r

1. A fluid-operated switch comprising a tubular plastic casing providedat its upper end with plug means capable of supporting the switch in areceptacle, electrical lead means extending'axially through said plugmeans and terminating in a pair'of spaced terminals insulatively mountedwithin said tubular plastic casing and having their inner ends exposedto the interior, of the casing, means defining an opening in saidplastic tubular means, a first metallic spring member in said casingassociated with one of said spaced terminals and arranged for flexureand asecond relatively rigid member associated with another of saidspaced.terminals with each of said members being in proximity tothemeans defining said opening, a flexible sheath-like diaphragmencompassing a portion of said tubular plastic casing and sealing thecontacts therewithin, said flexible sheath being in close proximity tothe first metallic spring member and bowing said spring member againstsaid rigid member when pressure is exerted against said diaphragm. I

2. A fluid-operated switch as claimed in claim 1, wherein the meansdefining said opening in said tubular plastic casing extendslongitudinally of said casing.

3. A fluid-operated switch as claimed in claim 1, wherein the meansdefining said opening in said tubular plastic casing is disposed at theterminal end thereof.

4. A fluidwperated switch as claimed in claim 1, element adapted tosupport the relatively rigid wherein the metallic spring member consistsof a coil m r, ai plasti rod further including a concave spring. surfaceapproximating the curvature assumed by the 5 A fl id p t d Switch asclaimed in claim 1, flexible sheath when pressure is appliedthereagainst. wherein the plastic tubular casing includes a plastic rod5

1. A fluid-operated switch comprising a tubular plastic casing providedat its upper end with plug means capable of supporting the switch in areceptacle, electrical lead means extending axially through said plugmeans and terminating in a pair of spaced terminals insulatively mountedwithin said tubular plastic casing and having their inner ends exposedto the interior of the casing, means defining an opening in said plastictubular means, a first metallic spring member in said casing associatedwith one of said spaced terminals and arranged for flexure and a secondrelatively rigid member associated with another of said spaced terminalswith each of said members being in proximity to the means defining saidopening, a flexible sheath-like diaphragm encompassing a portion of saidtubular plastic casing and sealing the contacts therewithin, saidflexible sheath being in close proximity to the first metallic springmember and bowing said spring member against said rigid member whenpressure is exerted against said diaphragm.
 2. A fluid-operated switchas claimed in claim 1, wherein the means defining said opening in saidtubular plastic casing extends longitudinally of said casing.
 3. Afluid-operated switch as claimed in claim 1, wherein the means definingsaid opening in said tubular plastic casing is disposed at the terminalend thereof.
 4. A fluid-operated switch as claimed in claim 1, whereinthe metallic spring member consists of a coil spring.
 5. Afluid-operated switch as claimed in claim 1, wherein the plastic tubularcasing includes a plastic rod element adapted to support the relativelyrigid member, said plastic rod further including a concave surfaceapproximating the curvature assumed by the flexible sheath when pressureis applied thereagainst.